Carburetor



Nov. l, 193.8. E. JEDRzYKowsKl GARBURETOR Filed NQV. 23,1956

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charge of fuel through Patented Nov. 1,- 1938 UNITED lSTATES CARBURETOR Edmund J edrzykowski,

Chicago, Ill., assignor to International Harvester Company, a. corporation of New Jersey Application November 23, 1936, serial No. 112,256

7 Claims.

This invention relates to a carburetor. More specifically it relates to a particular construction designed to prevent an objectionable condition known as percolating.

Carburetors of the type used on vehicle engines generally include a fuel reservoir and they are located in a hood compartment in close proximity to the engine. During operation of the engine, the entire carburetor is cooled by a substantial current of air which the fan of the cooling system forces rearwardly over the engine. The carburetor is also cooled by the air which passes through the mixing chamber. It is obvious, therefore, that, during operation of the vehicle, the float chamber of the carburetor and the carburetor in general is cooled sufiiciently to prevent a temperature rise sufficient to boil or vaporize to any appreciable extent, the liquid fuel.

When operation of the engine is discontinued these cooling factors are not present and, as a result, the heatgiven oil' by the metal of the engine rapidly raises the temperature of the carburetor. A great deal of diflculty has been encountered due to temperature increases sufficient to boil the liquid fuel in the reservoir and in the communicating fuel passage. This action causes the fuel in the fuel passages to percolate, with the bubbles carrying liquid fuel through the nozzle. 'I'his "effect has recently received more recognition, due to the use of down-draft carburetors. In such carburetors, the fuel which is percolated through the nozzle, immediately after the vehicle is stopped and operation of the engine discontinued, flows through the carburetor mixing chamber downwardly through the manifold into the engine cylinder. The overload or flooded conditi-on often prevents it from being started, and is particularly undesirable because of oil dilution.

The principal object of the present invention is to provide a construction` designed to reduce the percolating action to a minimum and to remove the vapor produced thereby without disthe nozzle into the mixing chamber.

Another object is to incorporate the antipercolating feature with the air bleed system of an otherwise 4conventional carburetor.

Another object is to provide an air bleed construction which increases suction in the accelerating well during idling and part throttle operation of the engine, hastening the refilling of the accelerating well and increasing its capacity.

' This air bleed construction causes the well to respond to both the manifold vacuum and suction of the nozzle, improving the acceleration and. pick-up of the engine.

The above objects and others, which will be apparent from the detailed description to follow, are attained by a construction as illustrated in the drawing in which:

Figure 1 is a vertical section substantially through the center of the mixing chamber, being somewhat diagrammatic in order to show all of the fuel and air passages in a single drawing.

In the form shown, the antipercolating construction is embodied in a carburetor of the down-draft type. Said carburetor is made in two sections, the lower section A having a tubular portion Ill, in which a venturi I I is located. At the outlet end of the mixing chamber on the engine side of the venturi, a throttle valve I2 is positioned, to control mixture fiow to the engine. Integrally formed as a part of the lower section of the carburetor, a float chamber I3 forms a source of fuel supply. A float I 4 pivoted in said chamber is utilized to regulate the liquid fuel level therein. The upper section B of the carburetor has a tubular portion I5 in alignment with the mixing chamber. A choke valve I6 is mounted in said portion. An integral extension I'I from the tubular portion forms a cover for the fioat chamber I3. A fuel inlet passage I8 is cored in said cover, communicating with the float chamber. A needle valve I9 engaged by the float I4 controls the inlet of fuel through the passage I8.

The lower section of the carburetor is formed with a vertical cylindrical accelerating well 20. A metering jet or orifice 2l forms a communication between the bottom of the fioat chamber and the bottom of ythe well 20. Said jet is adjustable, being regulated by a threaded needle valve 22 extending outside the float chamber bowl for adjustment.

It will be understood that, when the carburetor has not been in operation, the liquid level in the accelerating well will be the same as in the float chamber I3. communicates through a metered orifice 24 with the well 2U intermediate its ends. Said passage extends upwardly to the top of the lower section of the carburetor and then downwardly, terminating in an outlet 25 adjacent the throttle valve I2 when it is in closed position. A conventional air bleed for the idle passage is providedby a valve control passage 26 communicating with the main air inlet and with the idle passage. A threaded needle valve 21 forms theidle adjust- An idle fuel passage 23 of the carburetor.

ment to regulate the amount of air drawn in through the passage 26.

A metering well.28 is mounted in the well spaced from the bottom and side wall thereof, being secured in position at the top and only Where it is threaded into a bore 30 formed in the lower section of the carburetor body. Said well is inserted and removed from position by removal o f a plug 3| at the bottom of the well 2U.

The metering well 28 is of the progressively uncovered air bleed type, there being a series of perforations 32 in the well beginning close to the top and extending to substantially the bottom of the well.

The hollow interior of the Well 2B communi Cates with a mixt-ure passage 33 formed in the carburetor. Said passage extends upwardly and laterally to the mixing chamber. A fuel nozzle 34 formed as a hollow tube is fitted into the outlet end of the passage 33 providing thereby a fuel discharge means terminating in the restricted portion of the venturi Il. It is understood that in an air bled jet of this type, the openings 32 are progressively uncovered as the fuel level is loW- ered in the well 20. The relatively large amount of fuel in said well serves to provide the excess fuel necessary for acceleration when the throttle is first opened.

A passage 35, formed in the lower section of the carburetor, communicates with the top of the accelerating well 20 and through a metered orifice 36 with a passage 3l formed in the upper section The passage 31 communicates directly with a balance tube 38 connecting the top of the float chamber with the main air inlet.

A passage 38 connects with the passage 35 between the metering orifice 36 and the well 2G and by means of a metered orifice 39 with the idle passage 23.

In the operation of a carburetor, as above described, when the engine employing the carburetor is stopped, the effect of the heat applied to thecarburetor is reduced to a minimum between suspension of the metering well 28 out of contact with the lower portion of the carburetor body. Heat, which reaches said well, must be transmitted downwardly from the top with the result that sufficient heat is ordinarily not transmitted to the metering well to produce any appreciable amount of percolation within the well.

Heat, of course, istransmitted to the carburetor with the result that boiling with percolation is effected in the main accelerating well 20. Due to the provision of the passage 35 communicating with the extreme top of the well 20, the bubbles and liquid fuel carried thereby rise upwardly through said passage. The gas escapes or is condensed, and the liquid returns to the accelerating Well or to the float chamber. As the bottom of the well 28 is closed any bubbles which rise from the bottom of the well 20 cannot pass upwardly into the well 28. Bubbles passing upwardly along the outer wall of the well 20 will not pass through the small metering orifices 32 into the interior of the well. The proper location of the passages and the orifices and their relative sizes are important features in a construction of this type. The principle is as illustrated, however, insofar as the novel feature of construction is concerned.

The air bleed 39 is in series with the main air bleed provided by the orifice 36. High vacuum in the idle passage 23 when idling increases the suction in the accelerating well 20, causing the fuel level there to rise. The idle `quantity of fuel available by this rise in level benefits the pick-up and acceleration particularly when there has been a great drop of engine speed. When the suction in the idle discharge chamber drops, due to sudden opening of the throttle Valve i 2 or change of engine speed, the suction. in the accelerating well 2U decreases, releasing an idle quantity of fuel therein to flow to the engine in addition to that normally metered ythrough the main fuel jet or adjustment. The important feature of this construction is that the Well action responds to either suction .at the nozzle, or to the manifold vacuum. When approaching full load from part throttle, the pressure in the manifold increases with the result that the idle bleed 39 back-bleeds into the well 20 in addition to the main air bleed 3E. Suction is thereby reduced in the accelerating well 20, releasing an additional quantity of fuel to flow besides that normally metered through the main fuel adjustment.

It is to be understood that applicant has shown and described only a preferred embodiment of his improvements in carburetors and that he claims as his invention all modifications falling within the scope of the appended claims.

What is claimed is:

l. In a carburetor and in combination with the carburetor body and the fuel discharge nozzle thereof, a float chamber, means for maintaining fuel at a predetermined level in said fioat chamber, an accelerating well, a metered communication between the bottom of said well and the bottom of the iioat chamber, a metering well located rin said accelerating well spaced from the bottom and side wall thereof and contacting the carburetor body only at its upper end, a fuel discharge conduit connecting the interior of said well with the discharge nozzle, said metering well formed with a plurality of progressively uncovered air bleeds, a balance tube communicating with the top of the float chamber, a conduit connecting the top of the accelerating well with said balance tube, and said conduit being provided with a metering restriction forming a main air bleed, an idling fuel supply conduit communicating with the accelerating well below the float chamber fuel level and with the mixture passageway, and a well reloading conduit communicating with said idling fuel conduit and with the conduit connected to the accelerating well.

2, I n a. carburetor and in combination with the carburetor body and the fuel discharge nozzle thereof, a float chamber, means for maintaining fuel at a predetermined level in said iioat chamber, an accelerating well, a metered communication between the bottom of said well and the bottom of the float chamber, a metering Well located in said accelerating well spaced from the bottom and side Wall thereof and contacting the carburetor body only at its upper end, a fuel discharge conduit connecting the interior of said well with the discharge nozzle, said metering well formed with a plurality of progressively uncovered air bleeds, an idling supply conduit communicating with both the mixture passage and the accelerating well below the float chamber fuel level and having an intermediate portion extending thereabove, and an accelerating well reloading conduit connecting the top of the accelerating Well with the idling supply conduit, said reloading conduit being provided with a metering restriction.

3. A down-draft carburetor comprising in combination a mixture passageway formed with a Venturi throat, a throttle valve below said venturi, a starting shutter above said venturi, a fuel nozzle located in the restricted portion oi the venturi, a float chamber means for maintaining fuel at a predetermined level in said doat chamber, an accelerating Well, a metered communication between the bottom of said Well and the bottom of the float chamber, a metering well located in said accelerating well, a fuel discharge conduit connecting the interior of said Well with the dis charge nozzle, an idle fuel conduit communicating with the accelerating Well at an intermediate point therein, said conduit extending upwardly above the normal fuel level and then downwardly terminating adjacent the edge oi the throttle rali/e when it is in closed position, said conduit being iormed with a metering jet adjacent the accelerating Well, a balance tube connected to the top oi the float chamber, a conduit connecting the top oi the accelerating well with said balance tube, said conduit being provided with a metering restriction forming a main air bleed, and a conduit communicating with said conduit between the accelerating well and said air bleed and with the idle conduit, said last named conduit being provided with a metering restriction forming an air bleed.

il. n downmdralt carburetor comprising, in combination with the carburetor bo, a mixture passageway termed with a Venturi throat, a throttle valve below said venturi, a iuei nozale located in tbe restricted portion oi the venturi, a noa-t chamber, means ior maintaining iuel at a predetermined level in said float chamber, an accelerating well, a metered communication between said well and the noat chamber, a metering well located in said accelerating well spaced from the bottom and side wall thereof and contacting the carburetor body only at .its upper end, said metering Well being closed at its bottom and being formed with a plurality of metering orifices spaced vertically along the side Wall, and a. fuel discharge conduit connecting the interior of said well with the discharge nozzle;

b. .il downndrait carburetor comprising,` in combination with the carburetor body, a mixture passageway iormed with a Venturi throat, a throttle valve below said venturi, a iuei nozzle located in the restricted portion oi the venturi, a float chamber, means for maintaining iuel at a predetermined level in said float ciber, an ac-Il celerating well, a metered communication between said well and the iloat chamber, a metering well located in said accelerating well spaced from the bottom and side wall thereof and contacting the carburetor body only at its upper end, said metering well being closed at its bottom and being formed with a plurality of metering oriiices spaced vertically along the side wall, an air bleed conduit communicating with the top of the accelerating well outside the metering weil for car rying away bubbles resulting from percolation, and a fuel discharge conduit connecting the interior of said well with the discharge nozzle.

d. n. down-tirait carburetor comprising, in combination with the carburetor body, a mixture passagewar formed with a 'Venturi throat, a throttle valve below said venturi, a iuel nozzle located in the restricted portion of the venturi, a :float chamber, means tor maintaining iuel at a predetermined level in said iioat chamber, an accelerating well, a metered communication ben 'tween the bottom oi said Well and the bottom oi the iloat chamber, a metering well ertending downwardly into said accelerating well spaced from the bottom and side wall thereoi and contacting the carburetor body only at its upper end, said metering well being closed at its bottom end against the entrance oi iuel or bubbles and being formed with a plurality of progressively uncov ered metering orifices spaced vertically along the side wall, and a iuel discharge conduit connecting the interior oi said well with the discharge nozzle.

"i". it down-droit carburetor comprising, in combination with the carburetor body, a mixture passageway formed with a Venturi throat, a throttle value below said venturi, a iuel nozzle located in the restricted portieri oi the Venturi, a

iloat chamber", means ior maintaining iuel at a predetermined level in said iloat chamber, an ac celerating well, a metered communication between the bottom oi" said Well and the bottom oi" the float chamber, a metering Well located in said accelerating Well spaced from the bottom and side wall thereoi and contacting the carburetor body only at its upper end, said metering well being closed at its bottom end against the entrance of iuel or bubbles, said metering Well beine i'ormed with a pluralitr ci progressively uncovered metering oriilces spaced vertically along the side wall, a iuel discharge conduit connecting the interior oi said well with the discharge nozzle, and a conduit With a metering restriction connecting 'the top of the accelerating well with the iloat chamber.

im JEDRZYKWSKI.

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